Unit Test (Solutions): Control and Coordination | Science Class 10 PDF Download

Time: 1 hour

M.M. 30

Attempt all questions.

• Question numbers 1 to 5 carry 1 mark each.
• Question numbers 6 to 8 carry 2 marks each.
• Question numbers 9 to 11 carry 3 marks each.
• Question number 12 & 13 carry 5 marks each

Q1: What is the function of the pituitary gland? (1 Mark)
(a) To develop sex organs in males
b) To stimulate growth in all organs
(c) To regulate sugar and salt levels in the body
(d) To initiate metabolism in the body

Ans: (b)

The pituitary gland releases growth hormone (GH), which promotes growth in bones and tissues throughout the body. It also controls other endocrine glands, making it essential for overall growth and development.

Q2: A female is suffering from an irregular menstrual cycle. The doctor prescribed her some hormonal tablets. Which option shows that the hormone she lacks in her body is from the endocrine gland? (1 Mark)
(a) Oestrogen
(b) Testosterone
(c) Adrenalin
(d) Thyroxin

Ans: (a)

Oestrogen is a hormone produced by the ovaries, an endocrine gland, and is crucial for regulating the menstrual cycle in females.

Q3: Name two tissues which provide control and coordination in animals. (1 Mark)

Ans: Nervous and muscular tissues are two tissues which provide control and coordination in animals.

Q4: Name the plant hormone that inhibits growth and also helps in wilting of leaves. (1 Mark)

Ans: The plant hormone that inhibits growth and also helps in wilting of leaves is known as abscisic acid.

Q5: Which is the largest and most prominent part of the brain? (1 Mark)

Ans: Cerebrum is the largest and most prominent part of the brain.

Q6: Why does the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron take place but not in the reverse direction? Explain. (2 Marks)

Ans: At the synapse, (functional junction between neurons) axon terminal comes in close proximity to the dendron terminal of next neuron. Axon terminal is expanded to form pre-synaptic knob and the other dendrite terminal forms post- synaptic depression.

Q7: State the two types of movements seen in plants. Give one example of each type. (2 Marks)

Ans: Two types of movements seen in plants are:

(i) Nastic movements are movements independent of growth that are non-directional and occur due to turgor changes, e.g., closing of leaves in response to touch stimulus in ‘touch me not’ plant.
(ii) Tropic movements or tropism are movements due to growth, that are directional and very slow, e.g., movement of a part of the plant in response to light.

Q8: Define phototropism. Name the plant hormone which is responsible for phototropism. (2 Marks)

Ans: Phototropism is the movement of a part of the plant in response to light. Shoots generally grow towards light and are said to be positively phototropic, while roots grow away from light and are said to be negatively phototropic.
The growth movement of the plant part (stem) is caused by the action of auxin hormone. Auxin causes cell elongation. Thus, causing growth of stem towards the light stimulus.

Q9: Mention three major regions of brain. Write one function of each. (3 Marks)

Ans: Brain is divided into three main regions forebrain, midbrain and hindbrain.
(i) Forebrain consists of cerebrum, olfactory lobes and diencephalon. Its main function is thinking and controlling various activities such as touch, smell, hearing, speech and sight.(ii) Midbrain controls reflex movements of the head, neck and trunk in response to visual and auditory stimuli.
(iii) Hindbrain has three centers called pons, cerebellum and medulla. This part is responsible for regulating respiration, maintaining posture and balance of body and controlling involuntary actions such as heartbeat, breathing, swallowing, coughing, sneezing, vomiting, etc.

Q10: A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the immediate changes that take place in its body so that the squirrel is able to either fight or run. (3 Marks)

Ans: When squirrel is in a scary situation then its nervous system stimulates the adrenal glands to secrete more adrenaline hormone into blood. This adrenaline hormone increases heartbeat, breathing rate, blood flow into muscles and causes liver to put more stored glucose into its blood. All these actions of adrenaline hormone produces a lot of energy in squirrel’s body. In this way, squirrel prepares itself for fighting or running away action.

Q11: Name any three endocrine glands in human body and briefly write the function of each of them. (3 Marks)

Ans: Three endocrine glands with their function in human body are as follows:

1. Thyroid gland: It secretes a hormone called thyroxine which regulates the metabolism of carbohydrates, fats and proteins in the body and so provide the best balance for nutrients and mental ability.
2. Adrenal gland: It secretes two hormones—adrenalin and corticoid hormones regulate blood pressure, heartbeat, breathing rate and carbohydrate metabolism.
3. Pancreas: It secretes two hormones—insulin and glucagon. Insulin hormone lowers the blood glucose level. Glucagon hormone increases the blood glucose level.

Q12: Why is chemical communication better than electrical impulses as a means of communication between cells in a multicellular organisms? (5 Marks)

Ans: In animals, the message communicated in the form of nerve impulses, from receptors to central nervous system and from latter to effectors is very quick. But nerve impulses can reach only those animal cells which are connected by the nervous tissue. These cells after generation and transmission of nerve impulses, take sometime to reset their mechanism before a new impulse is generated and transmitted. It means, cells cannot continuously generate and transmit electrical impulses. This is the reason most multicellular organisms use another means of communication called chemical communication. In chemical communication information spreads out throughout the body by blood and its effects lasts longer. Chemical communication is however slow but it can reach all the cells of body regardless of nervous connections.

Q13:
(a) Name the hormone which is released into the blood when its sugar level rises. Explain the need of Chemical communication in multicellular organisms the organ which produces this hormone and its effect on blood sugar level. Also mention the digestive enzymes secreted by this organ with one function of each.
(b) Explain the need of Chemical communication in multicellular organisms. (5 Marks)

Ans:

(a) Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the a-cells that regulates glucose levels in the blood.
In order for multicellular organisms to function properly, their cells must communicate. For instance, your muscles must contract when your brain sends a message to contract.
Pancreas produces insulin and p-cells which increase glucose in blood. It also – produces digestive enzyme (pancreatic amylase).

(b) Cell-to-cell signaling is a critical component of coordinating cellular activities. Through this communication, messages are carried from signaling cells to receiving cells, also known as target cells. This signaling occurs with proteins and other types of signaling molecules. Other things which happens in our body due to cell communication are – growth and development, cellular reproduction, tissue repair, sensing pain, etc.